Wife's 98 Jetta Wolfsburg (the one that stranded me in the blizzard, and pops outta reverse) gave me another suprise today. The cruise, for no appearant reason, simply decides to turn itself off (or not work). If you turn it off and back on there is a chance it might work again for a few minutes.
Anyone have any guesses?
Tim Wohlford '89 Golf '98 Jetta
Guesses you shall receive. There is an interlock switch in the brake pedal and, in the case of manual transmission, one on the clutch pedal. On some (but not all) VW's the brake light switch also connects to the cruise control. The clutch and brake pedal switches are "normally open" switches mounted in such a way that with the pedal at rest the switch is depressed (so, the "normal" state for these "normally open" switches is actually closed). The brake light switch is a "normally closed" switch mounted so that with the brake pedal at rest, the switch is depressed and thus "open" If either of these switches are out of alignment, the cruise control can shut off by itself. The clutch and brake switches are easy to find, as they have both electrical connections (2 wires each) and a vacuum hose going to them. The brake light switch is in the same vicinity, but is slightly larger and has only electrical connections.
My experience is with an A2, but ETKA shows that the A3 uses the same part numbers. When I installed cruise in my A2 I aligned the switches so that with the pedals at rest, the switches were about 1/2 mm from being fully depressed. The switches have threads and are simply screwed into a sheet metal bushing. To adjust, disconnect the electrical and vacuum connections and rotate the whole switch. There are detents to keep the switch in position once adjusted.
The brake light switch on mine is adjusted by simply yanking the plunger out a few notches or pushing it back in. I forgot to check if you use the same brake light switch as I, so yours may be different.
If proper switch alignment does not fix the problem, one or more of the switches are probably getting flaky. I don't know the price of these switches, but replacement is an easy job.
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